Dear Customer
Selecting fine audio equipment, such as the unit you have just purchased, is only the beginning of your
musical enjoyment. Now is the time to consider how to maximize the fun and excitement your equipment
has to offer.
AUTOTEK and the Electronic Industry Associations Consumer Electronic Group want you to get the most
out of your equipment by playing it at a safe level, a level that lets the sound come through loud and clear
without annoying blaring distortion; most importantly, without affecting your sensitive hearing.
Sound can be deceiving. Over time your hearing “comfort level” adapts to higher volumes of sound, what
may have sounded “normal” can actually be too loud and harmful to your hearing. Guard against this by
setting your equipment at a safe level BEFORE your hearing adapts.
To establish a “safe level”:
• Start your volume control at a low setting.
• Slowly increase the sound until you can hear it comfortably and clearly, and without distortion.
• Once you have established a comfortable “sound level”, make a note of this position and do not go
above this setting.
Taking a minute to do this will help you to prevent hearing damage in the future. After all, we want you
listening for a lifetime.
Introduction
Your Autotek STEALTH amplifier has been designed to give you very high performance, and valuable
features, at a reasonable price. Take the time to read over this brief set of instructions, and you will get full
enjoyment from your system.
Installation
The quality of the installation will affect system performance and reliability. You may wish to contact a
dealer or professional installer. The amplifier is generally mounted in the rear trunk area but can be
mounted in any convenient area such as beneath a seat. Please be sure to locate this unit where you have
reasonable air circulation and protection from any hazard with moisture. When considering the mounting
location you should minimize the length of the power supply and speaker leads. It is important to ensure
that the cooling fans or the heat sink are not against a panel or a surface preventing air circulation. Mark the
location fro the mounting screw holes by using the amplifier as a template. Drill #29 or 9/64” diameter
holes at the marked locations and firmly fasten the amplifier in place with the mounting screws supplied in
the accessory kit. (Refer to Fig. 1)
Caution
Before drilling or cutting any holes investigate the layout of your automobile thoroughly; take care when
working near the gas lines or hydraulic lines and electrical wiring.
Warning
This power amplifier has a protection feature to prevent any damage form misuse or faulty conditions—
excessive heat, short circuited speakers or overload. If the nit senses one of the above conditions, the
protection indicator will light and the system will shut down. To diagnose the problem turn all levels down,
all power off and check the installation for possible wring mistakes or shorts. In the event the amplifier
shuts down due to excessive heat under adverse conditions simply allow time for the unit to cool down at
which time the protection indicator will not light.
Fig. 1 Installation of amplifier
Power Supply Connections
The +12VDC and ground wires should be heavy gauge standard copper wire with heavy insulation. The
wire gauge should be 4AWG for the 300.S, 400.S, 500.S or larger. In addition it has a 12V remote control
wire and it should be 14AWG-18AWG. It is preferable to have longer speaker wires and shorter power
supply wires to minimize power losses.
+12V Power
This wire is usually connected directly to the positive battery terminal. Ensure that the + power supply wire
is fused via an assigned fuse in line with the + power supply wire. This connection must be completed by
using spade lug with insulating sleeve.
Ground
This connection must be completed by using spade lug with insulating sleeve. This wire is the electrical
ground and must be fastened securely to the vehicle chassis. The best method is to use a shelf threading
sheet metal screw since the threads cut into bare metal. Ensure that all paint coating or other insulation is
removed from around the hole are and using self tapping screw, securely affix the bare wire ends to the
vehicle chassis. Use as short a piece of cable as possible—use the same gauge as for the +12V.
Remote
Many radios or other music sources have an output terminal for connection of the remote turn-on of the
power amplifier. If a radio doesn’t have a remote turn-on feature, then you can use the antenna relay wire
which activates the antenna motor. But you must take notice if the power antenna retracts when the tape
player is operating. In this case, you can’t use the antenna relay wire to operate the remote turn-on.
Power Input Connection
Fig. 2 Power Input Connections
Caution
First make +12V wire connection then the ground connection and finally the remote connection.
Furthermore the +12V wire must always be fused at the battery for protection against possible damage. If
you need to replace the power fuse, replace it with a fuse of the same value. Using a fuse of a different type
or rating may result in a serious hazard.
This amplifier has two types of signal input terminal. RCA connector for low input. Adjustment of input
levels is accomplished by the gain control of both channels. Adjusting this control allows the amplifier gain
to be controlled to match and balance both channels.
The RCA input connector should be used when connecting the radio/cassette line out and this connection is
usually made by using RCA-RCA connector wires. RED connector is used for RIGHT channel and
WHITE connector is used for LEFT channel.
DOTTED LINES SHOW 4-SPEAKER CONNECTIONS.
IN THIS CASE, IT IS BETTER TO USE 4 ohm SPEAKER TO
PREVENT ANY DAMAGES.
Fig. 4 Speaker Output Connections—MONO Mode
• The amplifier can be used in the STEREO and BRIDGED mode as shown in Fig. 4, Fig. 5.
• The speaker wires should be connected to the speaker terminal on amplifier.
• Notice that most speakers have a polarity marking such as “+” or a dot on speaker terminals and
these markings denote the positive terminals of the speaker and are used as a guide to phase the
speakers. Improper phasing causes a loss of bass response.
• When used in the BRIDGED mode the speaker wires should be connected to the output terminals
of the amplifier as shown . (Ref. To Fig. 5)
• When operating 4-speaker system, the impedance of the speaker is an important factor. Do not use
less than 2 ohm in the mono mode.
• Do not use speakers in parallel for less than a 1 ohm load per channel in the stereo mode.
• Too low impedance loads will cause excessive heat radiation from the amplifier and the protection
circuit will be operated to prevent damage. In this case, you must reduce the volume to the proper
level.
Caution
Be careful not to connect speaker (-) to the ground chassis.
1. RCA Line Output Jacks
Full range output from channel L + R inputs is provided at Line Out Jacks
2. RCA Low Level Input Jacks
It allows left and right inputs to be connected to the amplifier using RCA plugs.
3. Input Level Control
It allows for the adjustment of the gain of both channels to match the output level of the source.
4. High Variable Controls
Adjust the crossover frequency of the High Pass output only, from 75Hz to 750Hz.
5. Low Variable Controls
Adjust the crossover frequency of the LOW pass output only, from 40Hz to 150Hz.
6. Bass Boost Controls
Adjust the sub boost level of the selected frequency output from 0dB to + 18dB.
7. X-over switch
a) Low position: Allows for the control of the low pass frequency range (40Hz-150Hz) by
using the Low Variable.
b) Flat position: Allows for full range pass through.
c) High position: Allows for the control of the high pass frequency range (75Hz-750Hz) by
using the High Variable.
8. Subsonic Filter
It allows to delete the frequency under 35Hz for Subwoofer protection.
9. Power & Protection indicator
It has two color indicator and the Green indicator indicates amplifier has turn on signal. The Red
indicator indicates the fault operation of the amplifier. When the fault conditions (overload,
excessive heat or short circuit of speaker) arise, the protection circuit is engaged to protect both
the speakers and amplifier against damage.
10. Fuse
It protects both the amplifier and automobile electrical system from fault conditions. Use a
standard automotive fuse, 300.S:30A, 400.S:40A, 500.S:40Ax2.
11. Power connection
Connects +12VDC power wire from the battery and also connects ground wire from a suitable
ground point on the chassis.
12. Remote connection
Connects the control wire which allows the amplifier to be turned on and off by the radio cassette
player.
13. Speaker Terminal
It allows the connection of speakers to the amplifier.
SPECIFICATIONS
STEALTH 300.S 400.S 500.S
*Audio power output per Channel,
both channels driven at 14.4VDC.
- 4 ohm Stereo, 12.0volt 20Hz-20kHz <.018%THD 50watts/ch 75watts/ch 150watts/ch
- 2 ohm Stereo, 14.4volt 20Hz-20kHz <.02%THD 108w/ch 150w/ch 320w/ch
- 1 ohm Stereo, 14.4volt 20Hz-20kHz <.05%THD 182w/ch 236w/ch 400w/ch
* Signal to Noise Ratio >90dB
* Frequency Response 10Hz-40kHz, ? 1dB
* Crossover: Separate
- High Pass 75Hz-750Hz Variable
- Low Pass 40Hz-150Hz Variable
- Slope 0-12db OCTAVE
- Subsonic Filter 35Hz (-3dB)
- Bass Boost 0-18dB Variable
* Input Sensitivity 200mV-4Volts Variable
* Input Impedance
- Low level input 22KI ohms
* Damping Factor 180 into 4 ohms
* Channel Separation >70dB
* Power Supply Consumption
(Bridge RMS) 27A 36A 76A
* Fuse Rating 15Ax2 20Ax2 40Ax2
* Dimension (W 10.5” 10.5” 10.5”
* Dimension (x H 2.3” 2.3” 2.3”
* Dimension (x L inch) 13” 13.8” 17.3”
** 1. These specifications can be changed without notice.
** 2. Please note that the features shown in this manual may vary from model to model.
We Want You Listening for a Lifetime
Used wisely, your new sound equipment will provide a lifetime of fun and enjoyment. Since
hearing damage from loud noise is often undetectable until it is too late, this manufacturer and the
Electronic Industries Association’s Consumer Electronics Group recommend you avoid prolonged
exposure to excessive noise. This list of sound levels in included for your protection.
Decibel
Level Example
30 Quiet library, soft whispers
40 Living room, refrigerator, bedroom away from traffic
50 Light traffic, normal conversation, quiet office
60 Air conditioner at 20 feet, sewing machine
70 Vacuum cleaner, hair dryer, noisy restaurant
80 Average city traffic, garbage disposals, alarm clock at two feet.
THE FOLLOWING NOISE CAN BE DANGEROUS UNDER CONSTANT
EXPOSURE
90 Subway, motorcycle, truck traffic, lawn mower
100 Garbage truck, chain saw, pneumatic drill
120 Rock band concert in front of speakers, thunderclap
140 Gunshot blast, plane
180 Rocket launching pad
Information courtesy of the Deafness Research Foundation.
/
